The following background description constitutes a description of the background to the present invention, and thus need not necessarily constitute prior art. Engines, such as for example engines comprised in vehicles or ships, are usually equipped with an exhaust purification system which is arranged to purify exhausts from an engine in the vehicle.
There is a number of threshold values for emission levels of particles, substances and/or compounds, which have been established by authorities. Vehicles must comply with these emission levels in order to travel on the roads. Additionally, vehicle owners and/or drivers are also environmentally aware, and keen to avoid emitting more exhausts than necessary when a vehicle is used. It is therefore important that the exhaust treatment system can purify the exhaust stream from the engine efficiently before it is released into the surrounding air.